The flight attendants, members of the Association of Flight Attendants, last week staged demonstrations at four key US Airways airports. They still work under separate contracts despite a 2005 merger between US Airways and America West. They have rejected two tentative contracts this year, with a margin of just 50 votes in the second election.

A key issue has been that the airline, seeking a merger with AMR ( AAMRQ.PK), has signed a tentative contract with American flight attendants, but has not signed one with its own flight attendants.

While strike vote approvals are common, strikes themselves are rare.

"US Airways Flight Attendants are determined to do whatever it takes to get our long overdue contract," said Roger Holmin and Deborah Volpe, presidents of the two flight attendant groups, in a prepared statement released Tuesday. "Seven years after the supposed merger of America West and US Airways this management hasn't gotten it done.

"We don't want to strike," the two leaders said. "We want to work for a successful airline -- but the airline will never be successful when its frontline workers are hurting. Profits are soaring but flight attendants still shoulder the sacrifices forced through bankruptcy a decade ago as well as disparate, industry-low pay of a first contract from 1999. It's a black eye for US Airways and no foundation for a new marriage with American."

The National Mediation Board has the ability to restart negotiations after the failed contract vote in May, but so far it has not done so. However, given the narrow margin in the May vote, it seems unlikely that the NMB would enable the procedure that could lead to a strike. The AFA said Tuesday that "it is prepared to return to negotiations with a focused proposal that meets the primary concerns of flight attendants."

US Airways spokeswoman Michelle Mohr emphasized that a strike is not imminent. "The National Mediation Board has not released the union to strike and therefore there will be no operational or flight disruptions during the holiday travel season," Mohr said, in a prepared statement.

"The union has told our flight attendants that the strike vote is about positioning at the bargaining table and not about striking and the union has not requested that the National Mediation Board cease the mediation and negotiations process," she said.